• Journal of the Korean Chemical Society
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• v.47 no.5
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• pp.447-459
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• 2003

Generalized 2D correlation spectroscopy has been applied extensively to the analysis of spectral data sets obtained during the observation of a system under some external perturbation. It is used in various fields of spectroscopy including IR, Raman, UV, fluorescence, X-ray diffraction, and X-ray absorption spectroscopy (XAS) as well as chromatography. 2D hetero-spectral correlation analysis compares two completely different types of spectra obtained for a system under the same perturbation. Because of the wide range of applications of this technique, it has become one of the standard analytical techniques for the analytical chemistry, physical chemistry, biochemistry, and so on, and for studies of polymers, biomolecules, nanomaterials, etc. In this paper, we will introduce the principle of generalized 2D correlation spectroscopy and its applications that we have studied.

• Journal of the Mineralogical Society of Korea
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• v.20 no.4
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• pp.313-325
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• 2007

In order to have better insights into adsorption of organic molecules on kaolinite surfaces, we performed quantum chemical calculations of interaction between three different model clusters of kaolinite siloxane surfaces and benzyl alcohol, with emphasis on the effect of size and lattice topology of the cluster on the variation of electron density and magnetic shielding tensor. Model cluster 1 is an ideal silicate tetrahedral surface that consists of 7 hexagonal rings, and model cluster 2 is composed of 7 ditrigonal siloxane rings with crystallographically distinct basal oxygen atoms in the cluster, and finally model cluster 3 has both tetrahedral and octahedral layers. The Mulliken charge analysis shows that siloxane surface of model cluster 3 undergoes the largest electron density transfer after the benzyl alcohol adsorption and that of model cluster 1 is apparently larger than that of model cluster 2. The difference of Mulliken charges of basal oxygen atoms before and after the adsorption is positively correlated with hydrogen bond strength. NMR chemical shielding tensor calculation of clusters without benryl alcohol shows that three different basal oxygen atoms (O3, O4, and O5) in model cluster 2 have the isotropic magnetic shielding tensor as $228.2{\pm}3.9,\;228.9{\pm}3.4,\;and\;222.3{\pm}3.0ppm$, respectively. After the adsorption, the difference of isotropic chemical shift varies from 1 to 5.5 ppm fer model cluster 1 and 2 while model cluster 2 apparently shows larger changes in isotropic chemical shift. The chemical shift of oxygen atoms is also positively correlated with electron density transfer. The current results show that the adsorption of benzyl alcohol on the kaolinite siloxane surfaces can largely be dominated by a weak hydrogen bonding and electrostatic force (charge-charge interaction) and demonstrate the importance of the cluster site and the lattice topology of surfaces on the adsorption behavior of the organic molecules on clay surfaces.